Autothermic cracking reactor



Oct. 23, 1951 K. I I-IARTWIG ET AL 2,572,338

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Patented Oct. 23, 1951 AUTOTHERM'IC CRACKING `REACTOR Kar-11T. Hartwig, Glen Ellyn, and Ted B. Haufe, WesternSpringS., ill., assignors to -Universal Gil Products Company, Chicago, Ill., a corporation of Delaware Application 'J-u'ly "28, 1950, SerialNo.` 176;'3'38 This invention relates to an improved :type :of reactor :suitable 'for Veffecting the mixing .and Thigh temperature conversion of l"gaseous react- 4ant :streams The apparatus is particularly adapted for use in effecting the autothermic 'or foxidative cracking of *a lga'seous :hydrocarbon stream -in -admixture with a controlled oxygen -or air stream. Y

JThe autothermic cracking -o'f a hydrocarbon Lstream, such as ethano, propane, butano, and `the like, may 'be carried out iin "the 'presence of v4an oxidizing stream of vair -or oxygen, having a Vcontrolledoxygen content, ito provide Ian :exothermic reaction by the Aburning of rat Vleast -a 'portion of *the hydrocarbon fstream -to 1in turn produce heat Lfor an fendotherniic cracking of 'the remaining portion of 'a hydrocarbon stream, "and 'thus produce more valuable products. 'For example, prepa-nein admi'xture lwith air `may ibe cracked 'to make Ia supplementary-gas to meet vpeak load demands for gas companies -or the like; while for npetroleum-chemical manufacturing companies, it may be :desirable to effect the cracking -of ethane, or other available vola-tile hydrocarbons, to in turnproduce alhigh yield lof ethylene-which `may 5be used as a lstz'trting material 'forthe manufacture -of alcohol, anti-'freeze mixtures, or `various plastic products. rIh'ere are of vcourse many types "of lreactors land fcon version chambers which are in usefor have been Vused in vconnection 'with fthe mixing and cracking of Vgaseous hydrocarbon streams, however, many of these reactorsareconstructed -suchthat Vthey are fno't `readily assembled =or disassembled *for maintenance purposes. Also, most ytypes o'f .i

`reactors do not have any vmeans for adjusting the lVolume of the mixing v-zone in order to obitainoptimum mixing and conversion conditions.

It is a principal object of the Ipresen-t invention to lprovide a lined reactor chamber which -is adapted to fe'iect fthe rapid intimate vmixing .of reactant streams 2in order 'to --carry Yout -eliciently a resulting high temperature -'conversio'n.

It is falso la principal Iobj-ect of the present 'invention 4to provide fa construction which permits the Vadj.ustinent'of .the lvolume of the mixing 4zone,:so that maximum :conversion conditions "for 'the reactant streams may be effected. In addition the improved design vprovides assembly features which permit fready accessa'bility to the interior of Athe chamber for Ymaintenance purposes.

Briciiy, the .improved .reactor Lof invention comprises in combination, fan elongated pressure within the :frusto-conicalsection opposite the -p'erforations therein, the baille lthereby forming -a restricted annular shaped :mixing zone Pthat increases Yin volume 'toward rthe lreaction :section of the chamber, and product `outlet .means vin -the end of said reactor chamber opposite .the inlet end.

In a preferred `embodiment Aof the .improved reactor, the `double-ended cone shaped deector,

.forming the Aannular yshaped .mix-ing .zone of ,the

unit, is supported ,on `an vopen-ended tubular conduit which extends `concentrically within the first mentioned Ainner vreactant .stream inlet conduit. The open-ended .tube terminates Iat Lthe interiorfend of thedouble-ended'coneshaped l'oalie and providesmeans `for introducing a ame or igniting Lgas .into the `lend :of the .reactor .at -the end of the mixing zone.v .Also .in accordance with this particular feature of the ,present linvention, the support -tube is made adjustable with respect to the endof .the .reactor .chamber such that the cone shaped ybaiiie which is positioned thereon may ybe `moved inwardly -vor .outwardly with respect to the truste-conical.section, to in turn provide a .variable volume .mixing zone. An :igniter tube .is positioned within the supporting tube, and -provides means for .-igniting a -gas stream rin starting np the unit f.tor oxidative `or rautothermic cracking Jpurposesl Where (the Vimproved reactor is used for the autothermic cracking of ,fa hydrocarbon stream. ito produce, for :exam-ple, -.et-h-ylene, the oxygen :containingor air stream is :preferably introduced through the inner -inlet cond-uit :and :the VIhydrocarbon stream passed through the-.outer conduit, fas the annular-shaped stream being introduced through the .oriticesor per-forations in fthe-.narod section. Thus, :the hydrocarbon stream .is v'in'- troduced :into the 4=air stream as a r:plurality of jeta-like streams. The "size fand spacing of the merforations :or jorifices yare such that 1the .mass velocity ratios tof the hydrocarbon to Aair in the tightchamber havinginternal refractory lining, lilixing zone :is ,preferablylin Vthe-,range of 1.5 4to Referring now to the drawing, there is indicated Y one embodiment of the improved reactor apparatus, comprising an elongated body section I, with a removable inlet head 2 and a removable outlet head 3. heads each have suitable anges, so that the heads may be removably attached to the elongated body section in a pressure tight manner. The entire reactor chamber is also lined with a suitable refractory type of insulation. In this instance, a

vthick insulating material 4 is shown adjacent the -wall I, while a harder surface insulating and refractory material 5 is shown as an interior lining to form the internal cracking or conversion zone 6. The outlet head 3 has a metallic liner l,

-preferably of alloy material which extends inside the chamber to provide a ared section 8 which Ymeets and contacts the interior lining 5.

A bent section or collar section 9 provides a metallic portion suitable to bear againstthe end ofthe refractory liner 5 and at the same time hold a bloc-k insulating type of material I within the interior or enclosed portion of head 3. This construction is of vadvantage in providing a readily removable type of head, which in turn permits the insulation IU to be held and maintained with the head 3.

The upper head 2 has a concentric inner conduit Il and a concentric exterior conduit I2 extending therethrough in a manner forming gas passageways for introducing gaseous reactant streams to the interior of the reactor chamber. The inner conduit has a gas inlet nozzle I3,

:which in this instance is indicated as van air in- 1et,whi1e the exterior conduit l2 has an inlet nozzle I4, indicated as a hydrocarbon gas inlet.

"Atthe inside end of the inner inlet conduit v| I,

there is a flared or frusto-conical section I which extends from the end thereof inwardly and outwardly to contact the interior liner wall 5 of the central body section. The end of the flared 'section has a bent portion, or collar section I6, 'which in turn is adapted to bear against the end of the refractory insulation 5, while retaining a soft insulating material I1 within the removable headv portion. In other words, the inlet head section 2, with the gas inlet conduits, nozzles, flared section, etc., together with the insulating material |'|,"is attached to, or removed from connec- 'tion'with, the elongated body section I as a substantially separate unit.

'The interior end of the exterior conduit I2 terminates in a closure portion I8, which in turn butts against the flared section I5, whereby an annular shaped gas passageway I9, extending between the conduits and I2, is terminated and gas blowing therefrom passes into the interior of the chamber by way of a plurality of orifices or perforations 20. The orifices are spaced entirely around the throat portion of the conical shaped or iiared section I5 so that the gaseous reactant stream is distributed uniformly into the gas stream which in turn fiows through the n.-

'Ihe body section I and the removablev terior of the conduit into a mixing zone and thence into the reaction section. Also, in accordance with a preferred embodiment of this invention, a conically shaped baflie or deiiector 2| is positioned axially or concentrically within the frusto-conical or flared inlet section I5 whereby to form a restricted mixin`g`zone 22, which in turn is a cone shaped annulus increasing in volume as it widens in diameter. The deector 2| is a double-ended cone-shaped member so that the mixing zone widens very rapidly beyond the point of maximum diameter of the deector 2|, flaring to the inside diameter of the elongated chamber body portion I. The deliector 2| is of circular cross section, with the diverging inlet end thereof and the ilared section I6 forming the mixing zone annulus 22. The cone shaped inlet end of deilector '2| also has a slope equal to that of the slope of the frusto-conical section I5, in order to provide a uniform divergent annulus for the mixing Zone 22.

The deiiector 2| may be of an alloy steel construction suitable to withstand high temperature conditions or alternatively may be steel covered with a ceramic refractorytype of material such as indicated in the present drawing. The double ended cone shaped reflector or baille 2| is adjustably positioned within the interior of the unit by a supporting rod orr tube 23, which in turn can be propelled or retracted within the interior of the unit, with respect to the flared section I5. In this embodiment, the supporting tube 23 is indicated as being threaded and passing through a suitable threaded portion of a cover plate 24, which in turn may be bolted to or otherwise removably attached to the end of the interior inlet conduit I I. It is, however, not intended to limit the method of adjusting the supporting rod 23 and the bae or deiiector 2| by means of the threaded attachment, for obviously a packing gland or other adjustable means may be used for this purpose.

In addition to the particular feature and advantage of having the deflector member 2| adjustable with respect to the flared cone I5 so that the mixing zone may be changed in volume to provide optimum conversion conditions, it is a construction feature of the present embodiment to have the largest diameter of the deflector or baiiie member 2| smaller than the inside diameter of the interior` conduit such that by removing the cover plate 24 the supporting tube, the deflector 2|, and the internal portions thereof may all be readily removed from the interior of the chamber. Suitable ribs or spacing members 25 are placed exteriorly around the supporting tube 23 so that the latter may be held concentrically or axially within the conduit and the ared section I5.

Still another feature of a desired embodiment of the apparatus, is the concentric positioning of an ignitor tube 26 within the supporting tube 23, so that where the reactor is used as an oxidative or autothermic cracking reactor, the initial burning and start up of the oxidative reaction may readily be accomplished. For starting up purposes, a combustible gaseous stream may be introduced into the supporting rod 23 by means of a gas inlet 2l. Thus, the combustible gas passes downwardly around the ignitor tube 2B passing outwardly into the interior'of the reactor around the open end of the ignitor tube 26. Both the supporting and ignitor tubes terminate at the end of deilector 2|. Suitable means may be .pro' vided for passing puis of flame through the -ignitor ,tube 2.6 fand Llighti'ng'fthe .gas fbeinglfintro- 4V.duced through :inlet `nozzle y2:1' and 'theinterior fof 'ithe supportingtube l23. In an voxidative type .of Vcracking reaction, Vafter .the combustion of the hydrocarbon stream is commenced and the :reactor chamber is broughtzto temperature, the ignit- :ing flame may of course .be turned tof. In other it' is particularly adapted to :carrying Yout :an 'autothermic cracking `reaction as hereinbef'ore Ymentioned, so that more desirable products :may `be obtained from a saturated hydrocarbon :stream fsuch as ethane, propane., butane, 4or the like. In an autothermic conversion operation, the air Vor .oxygen-containing stream is preferably introaduced through the interior of the internal con- Aduit I I and the hydrocarbon gas stream is Yintroduced through nozzle .I4 and 'the annular passageway I9 so that it mixes with the oxygencontaining stream as a plurality of jet-like streams cominginto the air stream at substantially right angles thereto and `against the opposing bafiie or deflector member'Z l. Thus, there is considerable turbulence and rapid intimate mixing of the two gaseous streams within the restricted mixing zone 22. The number of orices and their size may of course be varied to provide different velocities from the orices and Various mixing ratios in the mixing zone. In the high temperature cracking of a normally gaseous hydrocarbon stream to provide ethylene, orifices are provided to pass the hydrocarbon stream into admixture with the air so that the mass Velocity ratio of hydrocarbon to air Within the mixing zone is within the range of from 1.5 to 5.0. Also, the mixing zone is adjusted so that the volume of the conically shaped annulus between the outer face of the deflector member 2| andthe interior face of the conically shaped flared or flared section i 5, provides a small mixing zone of less than 5% of the total reactor volume.

It may also be noted, that while the deflector member 2| is substantially circular in cross-section, in order to maintain a uniform spacing away from the face of the flared section I5, it may have some variations in shape to in turn aid in providing better mixing between the gaseous reactant streams. In other words, the outer end need not be of a smooth conical or ellipsoidal shape, for alternatively, the entire surface of the defiector member 2| may have certain irregularities or ribs or the like to provide increased turbulence in the deiiection of the reactant streams which impinge against it.

The reactor embodiment indicated in the drawing provides a downward Iiow of the reactant streams and the resulting product streams through the reactor, however, it may be pointed out that the yreactor may be well utilized in other positions and is not limited t0 the vertical positioning and a downward flow of reactant streams. In addition, a suitable packing material such as refractory metal or ceramic balls, or the like, may well be used within the interior of the elongated chamber to further aid in the intimate mixing of the reactant streams as they pass through the reactor. For example, in an autothermic cracking reaction the hot combustion gases from burning of a portion of the hydrocarbon stream must be intimately mixed with the remaining portion ofthe hydrocarbon stream in order that :it may be cracked to desired products.

.Flangeshave been shown as a means for 'connecting the various sections of the entire reactor, however, here again it is not intended to limit the construction to that type of removable attachment, for other clamping or connecting lmean'sjmay well be used. It is a specific feature' of the improved apparatus however, to have the vreactor constructed into the self-contained por- .tions as illustrated and described, such that either or both of the ends of the reactor may readily be removed for repair or inspection purposes, land readily reassembled without damaging the insulation within the interior of the chamber. Still another construction feature utilizes small gas inlet nozzles 28 and 29 in the upper and lower heads 2y and 3, respectively, such that*l an inert gaseous stream, such as steam or the like, may pe introduced into the interior of each head section and in turn prevent the passage of the reaotant streams or product streams from entering the crack or crevice at the juncture between the interior collar sections of the heads and the inner surface of the refractory liner 5 of the body section I.

We claim as our invention:

Y1. An improved reactor for mixing and effecting high temperature reactions between gaseous reactant streams, which comprises in combination, an elongated pressure tight chamber having internal refractory lining, a reactant stream inlet conduit extending into and discharging axially into one end of said chamber, a second reactant stream inlet conduit spaced concentrically around rst said inlet conduit and discharging an annular shaped stream into the end of said chamber, a flared frusto-conical section extending from first said inlet conduit to the inner Wall of said chamber, a plurality of orifices spaced around the smaller diameter inlet portion of said flared section, a cone-shaped deflector concentric within and spaced from said flared section and opposing said orifices therein, said deector forming a restricted mixing annulus that increases in volume toward the interior of said reaction chamber, and product outlet means through the end of said chamber opposite said inlet end.

2. The apparatus of claim 1 further characterized in that an adjustable supporting tube for said 'deflector extends longitudinally and axially through rst said inlet conduit and through said cone-shaped deflector, said supporting tube movable longitudinally within said chamber and providing thereby a variable volume mixing annulus.

3. An improved reactor for effecting mixing and high temperature reacting of gaseous streams, which comprises in combination, a reactor chamber having an internally insulated elongated body section, an internally insulated inlet end section, and an internally insulated outlet end section, with the internal insulation and lining means tapered for each of said sections whereby said end sections may have insulation extend into the ends of said ybody section and lap over a portion of the lining in the ends thereof, a gas inlet conduit concentric within said inlet end section having the interior end thereof flaring outwardly in a frusto-conical section extending to the inner wall of said elongated body section of said chamber, a second gas inlet conduit concentric around first said gas inlet conduit forming an annular gas passageway, the interior end of last said conduit terminating and contacting against the exterior face of said frusto-conica section extending from first said interior conduit, a plurality of gas orifices spaced around the small diameter throat section of said frusto-conical section and communicating with said annular gas passageway, whereby gas therefrom may be jetted through a plurality of orifices at substantially right angles into the gas stream passing through said interior conduit into said frustoconical section, a conically shaped deflector lmember spaced from `and concentrically within said conical section opposite said plurality of orifices therein and forming a conically shaped annulus suitable for a gas mixing zone, said defiector member supported and positioned within said frusto-conically shaped section by a long open-ended supporting tube extending axially through first said gas inlet conduit, said supporting tube movably connected and supported at the exterior end of first said gas inlet conduit whereby it may be moved in and out of said con- ;duit and thereby adjust the spacing of said deflector member with respect to said conically flared section, with said conically shaped annulus between said deflector member and said frusto-conical section providing a variable volurne mixing zone, and product outlet means 4throughthe end of said outlet end section of said chamber.

4.'The' reactor of c1aim'3 further characterized in that said axial supporting tube for said deflector member has an ignitor tube extending axially therethrough and spaced therefrom with an interior open-ended ignitor tube terminating at the inner open end of said supporting tube and at the end of said deflector member, and gas inlet means connects with the exterior end of said movable supporting tube whereby an igniting fuel may be passed through the annular space between said ignitor tube and the interior of said supporting tube.

5. The reactor of claim 3 further characterized in that said orices spaced around the smaller diameter portion of said flared section and passing gas from said annular passageway into said mixing zone provide area sufficient to effect a mass velocity ratio of gas passing therethrough with respect to gas passing through said interior gas inlet conduit of the order of 1.5 to 5.0, and said deilector member is adjusted with respect to said flared conical section providing a mixing zone annulus having a volume of less than 5% of the total interior reactor volume.

KARL T. HARTWIG. TED B. HAUFE.

No references cited. 

1. AN IMPROVED REACTOR FOR MIXING AND EFFECTING HIGH TEMPERATURE REACTIONS BETWEEN GASEOUS REACTANT STREAMS, WHICH COMPRISES IN COMBINATION, AN ELONGATED PRESSURE TIGHT CHAMBER HAVING INTERNAL REFRACTORY LINING, A REACTANT STREAM INLET CONDUIT EXTENDING INTO AND DISCHARGING AXIALLY INTO ONE END OF SAID CHAMBER, A SECOND REACTANT STREAM INLET CONDUIT SPACED CONCENTRICALLY AROUND FIRST SAID INLET CONDUIT AND DISCHARGING AN ANNULAR SHAPED STREAM INTO THE END OF SAID CHAMBER, A FLARED FRUSTO-CONICAL SECTION EXTENDING FROM FIRST SAID INLET CONDUIT TO THE INNER WALL OF SAID CHAMBER, A PLURALITY OF ORIFICES SPACED AROUND THE SMALLER DIAMETER INLET PROTION OF SAID FLARED SECTION, A CONE-SHAPED DEFLECTOR CONCENTRIC WITHIN AND SPACED FROM SAID FLARED SECTION AND OPPOSING SAID ORIFICES THEREIN, SAID DEFLECTOR FORMING A RESTRICTED MIXING ANNULUS THAT INCREASES IN VOLUME TOWARD THE INTERIOR OF SAID REACTION CHAMBER, AND PRODUCT OUTLET MEANS THROUGH THE END OF SAID CHAMBER OPOSITE SAID INLET END. 